Originally Posted by kschachn
Originally Posted by jbutch
My shortest OCI has been 2400 miles and QSUD
had already sheared/diluted from being a very thick 30 grade to a 20 grade (11.6 cst @ 100c to 8.62 cst @ 100c).
Which one is it? That's kind of the point of this thread.
Here's the latest UOA, it also includes past UOA.
Personally, I think it's more of a shear than fuel dilution as the Rotella that was used in the last OCI didn't drop as much in viscosity and the driving style was the same as all the other oils used before.
In reality, both fuel dilution and shear will occur in a TGDI imo. but after every GF5 OCIs, it dropped quite a lot in viscosity compared to the HDEO that was used last.
Currently have M1 ESP in the sump and I'm sure it will not shear as much.
There is a 140 pages thread with UOAs of the same engine that I have on NASIOC and the trend is the same as I'm seing, GF5-RC will shear while NON-RC will not as much and stay in grade.
If fuel dilution was the only factor in dropping the viscosity, wouldn't the viscosity drop as much for both RC and non-RC?